The purpose of this request is to obtain support for an electron microscope needed for collaborative research on the structure, organization, regulation and function of nucleic acids and nucleic acid complexes being performed in five departments at the University of California, Los Angeles. Research projects are organized in three areas. The first area is genome organization and RNA processing. This includes studies of the arrangement of histone genes in sea urchins, of the arrangement of immunoglobulin genes, the organization of adenovirus genes and their relation to message production and processing, various aspects of gene organization in SV40 virus genetic organizatin of Vibrio cholera, replication of the bacterial virus M-13 and the genetic organization of bacteriophage T-4 and cyanobacterial genes. The second area is gene expression. This involves RNA transcription from Drosophila chromosomes, organization and expression of genes coding for globin and for tumor cell products, the expression of mitochondrial DNA from trypanosomes, the expression of SV40 DNA and related human viruses, and the expression of messenger RNA from the arabinose operon of E. coli. The third area is the tertiary structure of nucleic acids and nucleoproteins. This involves the comparative structure of ribosomes from different sources, message location on the ribosome particle, the structure and arrangement of DNA in nucleosomes, the maturation of M-13 virus involving coat protein, cell membrane and viral DNA, and the structure of antibodies.